Skimmer for holding slag back during pouring metal



Sept. 20, 1955 R. PERRIN 2,718,389

SKIMMER FOR HOLDING SLAG BACK DURING POURING METAL FiledNo v 14, 1951 a 6 e x figilc I b e e Unified States Patent SKIMMER FOR HOLDING SLAG BACK DURING PoURING METAL Ren Perrin, Paris, France, assignor to Societe dElectro- Chimie dEl-ectro-Metallurgie et des Acieries Electriques dUgine, Paris, France, a corporation of France Application November 14, 1951, Serial No, 256,251

Claims priority, application France November 17, 1950 1 Claim. (Cl. 266-37) The present invention concerns the pouring of metal from metal processing apparatus of the tipping type, such as blower equipment of the type like those known under the name of turbo-hearth, and, generally to all tipping type furnaces and the like, with an acid or basic lagging, such as converters.

It is known, in metallurgy, that when pouring metal from tipping converters or furnaces, having an acid or basic lagging, it is highly important to prevent the slag covering the molten metal from falling simultaneously into the casting ladle.

This necessity is particularly imperative when subsequently treating steel, in the ladle, by means of a synthetic slag, molten or solid, since, if the slag from the converter gets mixed with the synthetic slag, it changes the nature thereof and decreases its efficiency.

The problem raised by stopping the slag when pouring is also highly important in the case where, after the working of steel in a basic converter or in a blower type apparatus of the same nature, there is merely introduced, in the ladle, an addition of metal containing a reducer such as Ti, Al, Si, Ca or similar metals, since, should phosphorus slag pass from the converter or other equipment intothe ladle, an undesirable re-phosphorizing of the steel would then occur.

It is, therefore, a prerequisite to satisfactory carrying out of the metallurgical operations, to avoid, when pouring the metal, any simultaneous flow of the slag remaining in the converter or other vessel, after the preliminary slagging off which is generally performed. In the case of basic converters, the problem has been tentatively solved heretofore by building up a darn, arranged in the pouring spout and consisting of lime, to which other materials are added if desired. These practices however, have disadvantages, and technical incidents are always to be feared. The entire slag is not always held back and, further, particularly when it is necessary to tilt the vessel to a large extent, for emptying it, the dam may collapse and the pouring is then defective.

The present invention concerns a simple device which overcomes these disadvantages most certainly and perfectly holds the slag inside the vessel and allows the latter to be emptied completely.

The device which is an object of the present invention essentially consists of a member or body of refractory material, the apparent specific gravity of which is higher than that of the slag but lower than that of the molten metal, and designed for fitting against the walls of the pouring spout or nose of the vessel and for being retained therein when the vessel is tilted over for pouring, a passage being provided for the molten metal between the bottom edge of said member and the lower part of the pouring spout, the height of the said member being sufficient to form, in said tilted position, a dam for the slag.

Another object of the invention is to provide a device enabling the accomplishment of the proposed aims and consisting in a floating dam for the slag in the pouring 2,718,389 Patented Sept. 20,. 1955 spout at the time of pouring and in providing an outlet for the molten metal under said darn, while keeping the level of said metal above said outlet.

' Before the pouring and after the preliminary slagging off, the member according to the invention is placed into the bath contained in the vessel employed, against the walls of the pouring spout of the latter.v Due to its density the said member tends to float above the metal and, when the vessel is tilted over for pouring the metal, it abuts against the walls of the pouring spout, leaving a free passage at the lower portion thereof. Provided the gradual inclination of the equipment is adjusted in such a manner that the level of the metal be always kept above the lower edge of the member, which is wedged in the pouring spout and, consequently, motionless, the metal flows out between said member and the base of the spout, whereas the slag is held in the vessel.

It will be realized that at the end of the pouring, when practically slag only remains in the vessel and that said slag may then flow out instead of the metal, the Vessel can be tipped back. However, should this be omitted, the slag which, at that moment'rnay flow underneath the obturating member is no longer subjected to a stirring with steel and therefore can no longer have any prejudicial action on the latter.

The obturating member, in accordance with the invention, may be a specially shaped body or may be obtained, for instance, from a parallelepipedic block, the angles of which. are cut out to confer on it the desired shape.

In order to increase the efficiency of this device, the sealing may be increased at the points where the edges of the obturating member come into contact with the walls of the pouring spout by disposing some lime at these points in the case of a basic lined vessel, or some refractory sand of any type in the case of an acid lined vessel.

The material from which the obturating refractory member is made, is preferably basic for a basic lined vessel and acid for an acid lined vessel. This choice, however, is not absolutely a prerequisite because of the tendency of slags to congeal when in contact with the cold material without attacking it seriously; it is possible, therefore, for instance, to use without any difiiculty a silicoaluminous material in the case of a basic converter.

A most economical and effective embodiment of the partial obturating member which is the object of the invention, consists, e. g., in manufacturing the said member by agglomerating to the desired shape, withcement, any refractory material such as sand, crushed old bricks, magnesian limestone or other similar material, and then allowing to dry. Moreover, according to such a type of embodiment, metal reinforcements, for instance steel bars, may be incorporated in the member to be manufactured, which increase both rigidity and weight thereof.

The invention is hereinafter described with more details by way of example, in the case of a converter, with reference to the appended drawings wherein:

Fig. l is a top view of an obturating member according to the invention;

Fig. 2 is a front view thereof;

Fig. 3 is an end view of the same;

Fig. 4 is a diagrammatic view on a horizontal section, along line IV-IV of Fig. 6, of the pouring spout of a converter in which is located an obturating member according to the invention;

Fig. 5 is a section of the same along the line VV of Fig. 6;

Fig. 6 is a vertical section on the line VIVI of Fig. 5.

As shown in Figs. 1 to 3, the obturating member 1, according to the invention, consists of a rectangular parallelepiped of refractory material meeting the above stated conditions as regards its density and the ends of which have been bevelled off along planes abcd and efgh, oblique with respect to both the longitudinal axis and the horizontal transverse axis of the member. The inclinations of the faces abcd and efgh is such that, after buttre'ssing against the walls of the pouring spout, they fit the shape of the spout.

The top surface afgd of the skimmer or obturating member 1 is in the shape of an isosceles trapezoid, the front edge dg of which is shorter than its rear edge a The bottom surface behc of the skimmer has the shape of an isosceles trapezoid, the front edge ch of which is shorter than its rear edge be and the area of the bottom surface behc is less than the area of the top surface afgd. The skimmer has two rectangular side surfaces abcd and efgh connecting the top and bottom surfaces. The side surfaces slope downwardly toward each other and also slope forwardly toward each other to conform substantially to the inner wall of the pouring nose 2 against which the skimmer 1 is applied and retained when the vessel is tilted during pouring. The skimmer provides a passage for metal between its bottom surface behc and the lower part of the pouring nose inner wall.

Figs. 4 to 6 show an obturating member 1, according to the invention, with its truncated faces abcd and efgh in the position which it assumes in the pouring spout 2 of a converter when tilted over for pouring. It will be seen that only the metal 3, the level of which is indicated at m can flow through the passage 4 provided between the member 1 and the lower portion of the pouring spout, whereas the slag 5, the level of which is indicated at 1, will be held back by the darn built up by the member 1.

What I claim is:

A skimmer for holding back slag while pouring metal from a tiltable vessel having a pouring nose connecting a pouring mouth with the vessel, the inner wall of the pouring nose tapering toward the pouring month, said skimmer being made of refractory material and having an apparent specific gravity higher than that of the slag but lower than that of the molten metal so that it floats freely on the metal, said skimmer having an isosceles trapezoid top surface, the front edge of which is shorter than its rear edge, an isosceles trapezoid bottom surface, the front edge of which is shorter than its rear edge and the area of which is less than the area of said top surface, and two rectangular side surfaces connecting said top and bottom surfaces, said side surfaces sloping downwardly toward each other and forwardly toward each other to conform substantially to the inner wall of the pouring nose against which said skimmer is applied and retained when the vessel is tilted during pouring, said skimmer providing a passage for metal between its bottom surface and the lower part of the pouring nose inner wall.

References Cited in the file of this patent UNITED STATES PATENTS 848,840 Moore Apr. 2, 1907 2,079,872 Quinn May 11, 1937 2,435,696 Pluta Feb. 10, 1948 2,494,270 Todd Jan. 10, 1950 2,554,836 McFeaters May 29, 1951 FOREIGN PATENTS 207,102 Germany Feb. 18, 1909 533,199 Great Britain Feb. 7, 1941 

